Known techniques for producing medicinal preparations containing practically water-insoluble drugs effective at digestive tract, which are employed in order to elevate water-solubility of the drugs and to promote absorption of the drugs via the digestive tract, include conversion into an amorphous form, inclusion within cyclodextrin, dissolution in organic solvents and dry- or wet-powdering.
EP-A-179583 (JP-A-61-91117) discloses a composition containing a practically water-insoluble drug, surfactant and a fat-soluble compound such as vitamin K or propylene glycol.
PF1022 Substance is a known cyclic depsipeptide compound represented by the formula (cf. EP-A-382173). ##STR1## This compound is one of the anthelmintic compounds which can be obtained, in accordance with the method described in EP-A-382173, from a culture of a microorganism isolated from a plant sample, which has been deposited with the Fermentation Research Institute, Agency of Industrial Science and Technology, Japan since Jan. 24, 1989 under the deposit number FERM BP-2671 in accordance with the Budapest Treaty.
PF1022 Substance exerts an anthelmintic effect on parasitic infection in digestive tracts of human, livestock, poultry, experimental animals, and companion animals, such as swine, horse, cattle, rabbit, sheep, goat, fowl, duck, turkey, rat, mouse, guinea pig, monkey, dog, cat, a small bird. PF1022 Substance, when used alone, shows a particularly marked anthelmintic effect on parasites in digestive tract of unigastric animals such as fowl, dog, cat and swine. In the case of rumenal animals such as cattle, sheep and goat, however, it is required to administer 5 to 10 times as much dosage as in the case of unigastric animals. This might be because PF1022 substance cannot attain a concentration or time enough to exert its efficacy in the infected sites in these rumenal animals, since it has an extremely poor solubility in water and therefore is hardly dissolved and dispersed in the digestive tract. Accordingly it is considered that the frequency and time of the contact of PF1022 substance with parasites can be increased by elevating its solubility in water and, as a result, the anthelmintic effect can be enhanced thereby.